The subject matter of the invention is a rotational viscosimeter for determining the flow properties of flowable mixtures having coarse grain components, especially of concrete mixtures comprising a drive having a torque measuring device, a pot and a central journaled, rotatable inner cylinder therein.
The conveying of fine particle suspensions having coarse particle portions, for example, the conveying of flowable concrete through pipes, is of increasing importance. The control of the properties of this type of flowable mixture is therefore necessary. Capillary viscosimeters are not suited to testing such materials because of the capillary geometry as well as the expense of measuring with measurements following each other in short order over a long period of time. Also known rotational viscosimeters consisting of a pot and a centrally journaled inner cylinder therein, also are not suitable to determine quantitatively the flow properties of mixtures having coarse grain portions, since the mixture to be tested in the gap between the bottom pot wall and the inner cylinder supplies an undesired contribution to the measured torque, which is detrimental to the results of the definable shear flow in the measuring gap.
There is known from U.S. Pat. No. 3,803,903 a rotational viscosimeter for non-newtonian liquids, consisting of a drive with a torque-measuring device, a pot and a central, journaled rotatable, inner cylinder therein, the bottom surface of which has a concave shape and is constructed as an air cushion for low friction rotor bearings.
This viscosimeter is not suited for measuring flowable mixtures having large particle components since the coarse grain components would settle on the bottom of the pot.
A similar rotational viscosimeter for lubricants is described in Austrian Pat. No. 122,893 in which the surface of the inner cylinder and/or the inner surface of the pot can be provided with channels, teeth or oil passages. This viscosimeter also is not usable for flowable mixtures having coarse grain components.
Therefore this invention is based on the object of providing a viscosimeter for determining the flow porperties of flowable mixtures having coarse grain components, especially concrete mixtures comprising a drive having a torque measuring device, a pot and a centrally journaled, rotatable inner cylinder therein which enables the obtaining of a trouble free measurement even at high viscosities, is sturdily designed and permits a large number of measurements over a long period of time in a simple manner.